Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Recovering from site failure
If all the hosts and storage fail at a site, use the following commands to reattach
the site after it comes back online, and to recover the disk group:
# vxdg -g diskgroup [-o overridessb] reattachsite sitename
# vxrecover -g diskgroup
The -o overridessb option is only required if a serial split-brain condition is
indicated. A serial split-brain condition may happen if the site was brought back
up while the private network link was inoperative. This option updates the
configuration database on the reattached site with the consistent copies at the
other sites.
See “Handling conflicting configuration copies” on page 243.
For more information about recovering a disk group, refer to the Veritas Volume
Manager Troubleshooting Guide.
Automatic site reattachment
The automatic site reattachment daemon, vxattachd, provides automatic
reattachment of sites. The vxattachd daemon uses the vxnotify mechanism to
monitor storage coming back online on a site after a previous failure, and to restore
redundancy of mirrors across sites.
If the hot-relocation daemon, vxrelocd, is running, vxattachd attempts to reattach
the site, and allows vxrelocd to try to use the available disks in the disk group to
relocate the failed subdisks. If vxrelocd succeeds in relocating the failed subdisks,
it starts the recovery of the plexes at the site. When all the plexes have been
recovered, the plexes are put into the ACTIVE state, and the state of the site is set
to ACTIVE.
If vxrelocd is not running, vxattachd reattaches a site only when all the disks at
that site become accessible. After reattachment succeeds, vxattachd sets the site
state to ACTIVE, and initiates recovery of the plexes. When all the plexes have
been recovered, the plexes are put into the ACTIVE state.
Note: vxattachd does not try to reattach a site that you have explicitly detached
by using the vxdg detachsite command.
The automatic site reattachment feature is enabled by default. The vxattachd
daemon uses email to notify root of any attempts to reattach sites and to initiate
recovery of plexes at those sites.
483Administering sites and remote mirrors
Failure and recovery scenarios